#include<iostream>
#include<map>

using namespace std;

class MyClass43 {
private:
    string add(string a, string b) {
        int l1 = a.length();
        int l2 = b.length();
        string long_str = l1 >= l2 ? a : b;
        string short_str = l1 < l2 ? a : b;
        int short_length = l1 <= l2 ? l1 : l2;
        int long_length = (l1 > l2 ? l1 : l2) + 1;
        int tmp_short = short_length;
        long_str = "0" + long_str;
        int carry = 0, i = 0;
        while (short_length > 0) {
            int l_pos = long_length - i - 1;
            int s_pos = tmp_short - i - 1;
            int tmp_carry = carry;
            carry = (carry + long_str[l_pos] + short_str[s_pos] - 2 * ('0')) / 10;
            long_str[l_pos] = (tmp_carry + long_str[l_pos] + short_str[s_pos] - 2 * ('0')) % 10 + '0';
            short_length--;
            i++;
            if (short_length <= 0 && carry) {
                for (int k = l_pos - 1; k >= 0; k--) {
                    if (long_str[k] == '9')long_str[k] = '0';
                    else {
                        long_str[k]++;
                        break;
                    }
                }
            }
        }
        while (long_str[0] == '0' && long_str.length() != 1) {
            long_str = long_str.substr(1, long_str.length());
        }
        return long_str;
    }

public:
    string test(string a, string b) {
        string c = add(a, b);
        return "0";
    }

    string multiply(string num1, string num2) {
        string ret = "0";
        string carry = "";
        for (int i = num1.length() - 1; i >= 0; i--) {
            int count = num1[i] - '0';
            for (int j = 0; j < count; j++) {
                while (ret[0] == '0' && ret.length() != 1) {
                    ret = ret.substr(1, ret.length());
                }
                ret = add(ret, num2 + carry);
            }
            carry += "0";
        }
        return ret;
    }
};